Landing system



S. E. ADAIR LANDING SYSTEM June 18, 1940.

Filed Feb. 10, 1937 m 5 WM 4 W 1 m W 4 M a x 4\ Rm WWW W0 n IA A L Ev WWA Patented June 18, 1940 2,25

LANDING SYSTEM Samuel E. Adair, Chicago, Ill., assignor, by mesneassignments, to Bendix Radio Corporation, Baltimore, Md., a corporationof Delaware Application February 10, 1937, Serial No. 125,112

7 Claims. (Cl. 177-352) This invention relates to the landing ofaircraft points, so that the beam l2 may be directed and more especiallyof airplanes, on landing down-wind from a position such that there isfields. An object of the invention is to provide adequate space behindit for landing the plane. means for guiding planes in landing, in a fogThe beam I2 is at a gliding angle, and the beam 5 for example, withoutthe use of radio, either as H1 at a flatter angle suitable for landing.

the sole means for guiding the planes or as an The two beams intersectin a zone l8 at the auxiliary emergency guiding means for use whenheight where the pilot should level ofi for landsomething goeswrong'with the radio blind landing, and at this intersection theyproduce a beat ing system. note in the detecting apparatus at a thirdand 1e This object is accomplished by the use of inl w r fr q e y whwould for example be 10 tersecting beams of super-sonic sound waves, i.e. 3,000 beats D e d f e b s n and I2 sound waves above audiblefrequencies, arranged are at frequencies of 15,000 and 13,000- At y in anovel manner s d s rib d b 1 t guide rate I prefer to select thefrequencies so that the the plane down on a gliding angle to a zone fbeat notes are at an audible frequency, and will intersection at theproper height for leveling off literally shout at the Pilot e it s t eto 15 for landing, the frequencies of the two beams belevel ing soselected as to produce at the zone of in- The Plane is Provided Wiiihdetecting means. tersection a beat note in the detecting apparatus ofany Suitable and Well-known character, at a third and lower (andpreferably audible) eluding microphones 22 d 24 at the w psfrequency,the indication of which warns the pilot The ph one f wh is dicated di-20 to l v l off, agrammatically at 22 as a diaphragm in Figure 3,

The above and other objects and features of may be arranged to be actedon from both Sides the invention will be apparent from the followingthrough a h g passageway 25 and leaddescription of the landing of aplane as illustrated ing from an intake passage 30 facing in the "5 inthe accompanying drawing, in whi h; rection of flight. The one passage,for example 25 Figure 1 is a diagrammatic vertical section 26, isProvided with an accoustical filter 32 through a landing field, in tplane of the signed to pass only the selected frequencies tersectingbeams of sound; (15,000 and 18,000) and the other passage 28 Figure 2 isa diagrammatic perspective view of With a filter 34 which Will not p ssese 30 a plane following one of the be ms; d quencies. A more desirablemethod is to em- 30 Figure 3 is a diagrammatic plan view of one y twofilters, one of w h pass s all fr wing-tip of the plane, illustratingthe arrangequcncies d iJhe other Of which passes ment of one of themicrophones for detecting the n the selected frequencies Thus ordinarysound waves. noises as well as air pressure entering the in- Fig. 4 is ahorizontal section of the wing ink passage 30 act equally on h id of e35 stallation shown in Fig. 3, showing the intake and microphone, andcancel themselves u w a filter passages together with the microphon thetwo frequencies to be detected act only on chamber. one side of themicrophone. Preferably the fil- As illustrated in Figure 1, the landingfield is ters 32 and 34 are tuned resonant chambers as provided withmeans, oi any well known charw l be understood. The w v so detected by40 acter, for generating two sets of sound waves of the rophone ay be ped in the 1 81 different frequencies (for example 15,000 and manner. tosh w n an indicator of y desired 18,000 per second) of supersonicfrequencies, and character n the instrument rd of h pl n which aredirected in beams l0 and H2, at difand to cause the beat notes toactuate a suitable ferent angles a and b to the surface of the field10nd pe iihe Pilot/S head telephones- Suit- 45 by means such asaccoustic projectors l4 and I6. l fi ers m y be u d to p the response fThe accoustic projector M and its power source the indicator at theselected frequencies. If the may conveniently be mounted on a soundtruck, Plane a y time goes above below the beam so that the beam may bedirected down-wind the effect of the sound beam on the microphone (sothat the plane will land headed into the will be appreciably less andconsequently this 50 wind in landing) from the edge of the field. willbe shown on the indicator. The indicator There may be a plurality ofprojectors It, armay also be arranged in a known manner to rangedannularly about the center of the field show a diflerence in phase inthe sound waves and facing outwardly, or means may be provided picked upby the two microphones so that if for mounting the same projector atdiflerent the plane is not go n direc y t he beam,

i. e. to the right or left, the microphone on one wing will pickup thebeam at a different part of the wave than the microphone on the other.

The pilot approaches the airport, flying into the wind, until he picksup the beam l2, and then flies straight into the beam until he reachesthe intersection it, where he levels off and follows beam it to alanding.

While one particular arrangement has been described in detail, it is notmy intention to limit the scope of the invention by that description, orotherwise than by the terms of the appended claims.

I claim:

1. That method of guiding a plane in landing on a field which comprisesdirecting, substantially at a gliding angle down-wind from a position inthe field leaving adequate landing space behind it, a sound beam at asupersonic frequency, directing a plane in a direction following saidbeam downward toward the field, directing at a flatter angle suitablefor landing and in the same direction as the first beam and intersectingthe first beam at a height where the plane should level off, from theedge of the field, a second supersonic beam at a frequency differingfrom the first frequency by such an amount as to produce a beat note atan audible frequency where the beams intersect, leveling off the planewhen said note is heard, and landing the plane approximately at saidflatter angle.

2. That method of guiding a plane in landing on a field which comprisesdirecting, substantially at a gliding angle from a position in the fieldleaving adequate landing space behind it, a sound beam at a supersonicfrequency, directing a plane in a direction following said beam downwardtoward the field, directing at a flatter angle suitable for landing andin the same direction as the first beam and intersecting the first beamat a height where the plane should level off, from the edge of thefield, a second sound beam at a supersonic frequency differing from thefirst frequency by such an amount as to produce a beat note at a lowerfrequency where the beams intersect, leveling off the plane when saidbeat note is detected, and landing the plane approximately at saidflatter angle.

3. A landing field having means for directing down-wind substantially ata gliding angle from a position leaving adequate landing space behind ita sound beam at a supersonic frequency, and having means for directingfrom the edge of the field behind said position a second beam at aflatter angle in the same direction as the first beam and intersectingthe first beam at a height suitable for leveling a plane off for landingand of supersonic frequency differing from the fre-' quency of the firstbeam by such an amount as to produce at the intersection of the beam abeat note at an audible frequency.

4. A landing field having means for directing substantially at a glidingangle from a position leaving adequate landing space behind it a soundbeam at a supersonic frequency, and having means for directing from theedge of the field behind said position a second beam at a flatter anglein the same direction as the first beam and intersecting the first beamat a height suitable for leveling a plane ofi for landing and ofsupersonic frequency differing from the frequency of the first beam bysuch an amount as to produce at the intersection of the beam a beat noteat a third frequency,

5. A landing field having means for directing substantially at a glidingangle from a position leaving adequate landing space behind it a soundbeam at a supersonic frequency, and having means for directing from theedge of the field behind said position a second beam at a flatter anglein the same direction as the first beam and intersecting the first beamat a height suitable for leveling a plane off for landing and ofsupersonic frequency differing from the frequency of the first beam bysuch an amount as to produce a beat note at a third frequency, incombination with a pair of detecting means adapted to be mounted inspace relationship on an aircraft approaching said field, said detectingmeans including microphones sensitive to said supersonic frequencies butinsensitive to other frequencies.

6. A landing field having means for directing substantially at a glidingangle from a position leaving adequate landing space behind it a soundbeam at a supersonic frequency, and having means for directing from theedge of the field behind said position a second beam at a fiatter anglein the same direction as the first beam and intersecting the first beamat a height suitable for levehng a plane off for landing and ofsupersonic frequency differing from the frequency of the first beam bysuch an amount as to produce a beat note at an audible frequency, incombination with a pair of microphones mounted in spaced relation on anaircraft approaching said field, and means for substantially restrictingthe output of said microphones to the respective frequencies ofsaidbeams.

7. A landing field having means for directing substantially at a glidingangle a position leaving adequate landing space behind it a. sound beamat a supersonic frequency, and having means for directing from the edgeof the field behind said position a second beam at a flatter angle inthe same direction as the first beam and intersecting the first beam ata height suitable for leveling a plane off for landing and of supersonicfrequency differing from the frequency of the first beam by such anamount as to produce a beat note at an audible frequency, in combinationwith a pair of microphones mounted in spaced relation on an aircraftapproaching said field, and acoustic filter means connected with saidmicrophones whereby the actuating energy impressed upon said microphonesis predominantly of the frequencies of the respective beams.

SAMUEL E. ADAIR.

